Company email (October 2012):
"We do not use animal products in any of our beers with the exception of a very limited amount of cask conditioned beer that is clarified with finings and is used as a special event product. Our beer is only produced here at the brewery in Saint Paul, MN."

[Note: yes, I know the responses are identical. So were the inquiries. That's what makes it funny]
Company email:
We adhere to a Bavarian purity law from the 1500s called the Reinheitsgebot, which states that beer is made from 4 things: malted barley or wheat, hops, water, and yeast. The only deviation from this occurs in our Scandia-we add coriander, bitter orange peel, and cardamom, and our Oatmeal Stout does contain some oatmeal. We do not add any animal products to our beer, including honey.

We are now offering some cask-conditioned beers at a few, select
bars-this beer does use isinglass (because it is conditioned in the cask and unfiltered). Again, the cask ale program is very, very limited, so the use of isinglass is rare. You would not accidentally get a cask ale from Summit, so no worries there.

Email 2:
That is strange, we got the same question worded the exact same way just a few months ago! Anyway, about our beer:

We adhere to a Bavarian purity law from the 1500s called the
Reinheitsgebot, which states that beer is made from 4 things: malted barley or wheat, hops, water, and yeast. The only deviation from this occurs in our Scandia-we add coriander, bitter orange peel, and cardamom, and our Oatmeal Stout does contain some oatmeal. We do not add any animal products to our beer, including honey.

We are now offering some cask-conditioned beers at a few, select
bars-this beer does use isinglass (because it is conditioned in the cask and unfiltered). Again, the cask ale program is very, very limited, so the use of isinglass is rare. You would not accidentally get a cask ale from Summit, so no worries there.